| Description |
The Bending Beam Rheometer (BBR) test is a recently developed test that is used to determine low-temperature behavior of asphalt mixtures. By knowing the low-temperature behavior, transverse cracking can be effectively predicted. Transverse cracking is a major cause of distress in wintertime and degrades the pavement structure. Significant research has shown that the BBR test can not only be used as a viable means of predicting this type of cracking, but also as a simpler and more economical method to address low-temperature pavement performance. However, as mentioned, the BBR test as used in this regard is relatively new, and needs to have standard specifications developed for the testing of the low-temperature properties of asphalt mixtures. The purpose of this study is to demonstrate both the repeatability and efficiency of the BBR test when applied to asphalt mixtures, in order to promote the development of standard specifications for its use in asphalt mixture low-temperature testing. The repeatability of the BBR test was verified to ensure that the results of BBR testing were consistent across different labs, different testing intervals, and duplicated tests on the same specimen. This was done by BBR testing a series of beams cut from lab prepared Super Gyratory Compactor (SGC) samples at two different labs. The results indicate that the BBR test is repeatable under the given circumstances. The widespread adoption of the BBR test requires efficient use of existing materials. Highway agencies prepare SGC samples for volumetric properties verification, as well as collect field core samples for asphalt pavement thickness verification. The BBR test, as it can use beams from both of these types of already collected samples, can be more easily adopted than other low-temperature tests that require extra samples to be obtained specifically for them. Both studies provided support for the creation of standard specifications for the BBR test as used in measuring low-temperature properties of asphalt mixtures. In addition, both studies encourage the widespread use of the BBR test as a means of accurately and efficiently measuring these properties. |
